1. Field of Invention
This invention relates to a broadband power combining method and power dividing and combining amplifier designed using such a circuit synthesis method.
2. Discussion of Related Art
High efficiency high power amplifiers have been widely employed in many radio frequency (RF), microwave and millimeter frequency applications. There have been many approaches and topologies proposed in previous works on the designs of multi-device power combining amplifier to meet various application demands. There have been several publications: Dupulis, “Stacked RF Power Amplifier”, U.S. Pat. No. 2006/0226905 A1, which described a stacked approach using two devices for RF power amplifier; Ky-Hien Do, “Wide Bandwidth, High Power Amplifier”, which proposed a combining topology for high power amplifier using multiple transformers that are connected in series (stacked) to increase the output voltage swing.
Many forms of power dividing and combining amplifiers are also known in the art. See: Takagi et al, “Microwave Power Combining FET Amplifier”, U.S. Pat. No. 4,803,443; Cripe, “Combining Circuit for Class-E RF Power Amplifiers”, U.S. Pat. No. 5,247,264; Stedman et al, “Power Combiner for Use In A Radio Frequency System and A Method of Constructing A Power Combiner”, U.S. Pat. No. 5,543,751; Tajima et al, “Amplifier Having Substantially Constant DC. To RF Conversion Efficiency”, U.S. Pat. No. 5,025,225; P. Haldi et al, “A 5.8 GHz Linear Power Amplifier in a Standard 90 nm CMOS Process using a 1V Power Supply”, 2007 IEEE Radio Frequency Integrated Circuits Symposium, pp. 431-434, as well as S. Kim et al, “An Optimized Design of Distributed Active Transformer”, IEEE Transactions on Microwave Theory and Techniques, Vol. 53, No. 1 Jan., 2005, pp. 380-388. All these references are incorporated by reference herein. However, none of existing solutions provide generalized solutions addressing the fundamental power combining problem: how to divide and combine voltage/current among multiple active devices to achieve specified power dividing/combining ratio over any given frequency bandwidth. Current design approaches either can only provide single solution for a given device structure within a very limited bandwidth, or can provide wide band responses at large cost of degraded power combining efficiency.